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Building blocks of life > DNA > Flashcards

DNA Flashcards

1
Q

who waas the pioneer of nucleaic acids?

A

Fredrick meisccher

Pheobus levene

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2
Q

what did fredrick meischner do?

A

wanted to isolate chemicals of white blood cells
isolated cells from surgical bandages
found it was acidic
named it nucleic acid

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3
Q

what did pheobus levene do?

A

identified DNA molecules have a phosphate sugar backbone, named this a nucleotide
propsed DNA is a reapeating unit
did the chemistry to work out components

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4
Q

purines

A

A,G

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5
Q

pyridamines

A

C,T,U

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6
Q

which way are the carbonds numbered

A

right to left

ending on the to one

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7
Q

which way do we read DNA

A

5 to 3 prime

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8
Q

evidence of DNA being heriditary experiment

A

2 strains of pneomococci causing pneumonia

griffths

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9
Q

pneumococci experminet detail

A

mouse infecjectd with either strain R or S
with strain S, die, with R survives
heat kill S and inject, still fine
mix r and s and kills

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10
Q

what is starin R and S

A

R is benign

S is virulent

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11
Q

what did the mouse pneumocci experiment show?

A

something from the dead S cells goes to the R cells to make them virulent and they can be revives

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12
Q

what did Avery do?

A

remove lipids and carbs from heat killed S cells
proteins, RNA and DNA remain
treat to remove either of these last three
obverse transformation or not

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13
Q

what did Avery find?

A

No protein: tranfomed
No RNA: tranformed
no DNA: nothing
proved proteins NOT heriditary but DNA is

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14
Q

what did hershey and chase do?

A

bacteriophage heriditay material

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15
Q

what did the bacteriophage heriditay material expeiment show?

A

the molecule transfered between bacterial cells was DNA and not protein
if replication continued, daughters would be radioactive due to DNA

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16
Q

what did edwin cargaff do?

A

work out the ratio of bases

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17
Q

how did the ratio of bases get woked out?

A

edwin cargaff
take tissues and extract the DNA and trea them
hydrolyse leaving free nucleotides
sepearate them using paper chromaotgraphy
measure the number of bases using UV spectromoetry

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18
Q

what did edwin cargaff conclude

A

amount/ percentage of bases differed between species and the poportions are always the same and add up to one

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19
Q

whatis the chargaff rule

A

amount/ percentage of bases differed between species and the poportions are always the same and add up to one

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20
Q

who all showed that DNA is hereidiatry material

A

griffiths
avery
hershey and chase

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21
Q

how did X-ray difffraction help show DNA structure

A

using crystal of the molecule the diffraction pattern is very unique
made two patterns of diffraction, A and B.
found helical shape

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22
Q

how did watson and crick made a DNA model

A

negative phosphates repel each other, these on outside
base pairs line up inside and are same equal lengths
mode made with tin plates, antiparalel chains

23
Q

features of watson and cricks DNA model

A 
two aniparalel strands
10 pairs per strand
riht handed helix
bases perpedicuar to helixal axis
helix not symetrical
minor and major groove
24
Q

what did mesleton and sthal show?

A

repication of DNA is semi-consevative

25
Q

what experiment showed semi conservative replication

A 
grew ecoli in N15
all DNA radio labelled
swap to N14 media
new dna now grows with this
centrifuge for density gradient
repeat wth new colony in N15
found at end that most DNA had half a half, some from parents and some from new in the growth media, showing semi-conservative
26
Q

why is replication complicated?

A

strands run in opposite directions

27
Q

how does polymerase work to overcome replication issues?

A

only reads 3-5 direction and synthesises 5-3
discontinuous way of working
causes the strands to swap over

28
Q

what is the central dogma

A 
information flow in cells
replication
transciption from DNA to RNA 
then translation into proteins
and reverse using revere transciption
29
Q

how gave evidce mRNA is the messenger?

A

elliot volkin

30
Q

what did elliot volkin do?

A

lysed cells, treated nucleic acids with NaOH
analysed with ion chromatography
after infection, large activity with synthesis of acids
DNA of phage transcrbed into mRNA

31
Q

how does transciption work?

A

one strand trascrbed in each gene

starts at defined point, promoter sequence

32
Q

what way is the DNA sense strand

A

5-3

33
Q

what way is the DNA anti-sense strand

A

3-5

34
Q

what way does RNA polymerase read

A

3-5 reading

35
Q

whaich way is translation to make proteins

A

5-3

36
Q

how do enzymes work on DNA

A

read 3-5

synthesise 5-3

37
Q

what is the new RNA strand complementary to?

A

DNA anti-sense

38
Q

what is the structure of mRNA in eukaroyotes

A

5 end cap methylation modification
3 prime untranslated region, AAUUAAA
equals end of transciption
poly A tail added for stability

39
Q

what is 5 end cap methylation used for

A

involved to get in ad out of the nucleuc

introns and exons too

40
Q

how are introns removed?

A

splicin via small nuclear ribonucleapproteins snRNPs

41
Q

what are the consequences of RNA splicing

A 
alternative proteins
new stop codons
reading frame changes
proteins with different modules or regulator elements 
different proteins from same genes
42
Q

whats alernatve splicing

A

allows eukaryotic organisms to increase genes by 2-3 times

43
Q

how were the number of amino acids worked out? and the genetic code features

A

Brenner and phage mutants

44
Q

what did brenner find?

A

code is degenerate, non-overapping and works in units of three

45
Q

what did Nirenberg work out?

A

how translation worked

46
Q

what did nirenberg do?

A

Poly U experiment
By measuring the amino acids that were incorporated into protein it was possible to show that the RNAs from different sources were making different proteins.

47
Q

ribosome structure

A

reads 5-3

parts:
- A site
- P site
- E site

48
Q

what is tRNA

A

uncodes the RNA and links correc amino acid

49
Q

three stages of translation

A

initiation
elongation
termination

50
Q

describe initiation of translation

A 
mRNA binds to small ribosomal subuni
complex binds to tRNA
binds to large sub-unit now
binds into P site
cycle to next part
51
Q

describe elongation of translation

A

next tRNA binds to next bases of rna filling site A
join two amino acids in chain
transloaction from site P to A
whole thing shifts
tRNA moves aong from A to P, another goes from E and dissociates

52
Q

order of binding sites on a ribosome

A

E, P, A

53
Q

describe the proces of termination in translation

A

continues untill reaches a stop condon
release factor binds to stop codon
dissocated from whole complex
cycle stops

54
Q

process of translation in short

A 
P site
chain moves
A site filled
translocation
E site
removal

Building blocks of life (17 decks)

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